This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A371826 #9 Apr 07 2024 17:43:57
%S A371826 1,2,8,35,170,872,4740,26994,161006,1001009,6476976,43480373,
%T A371826 302250196,2170406149,16070240276,122453910495,958755921686,
%U A371826 7701233828576,63381318474768,533793776053926,4595440308780620,40400161269188412,362367733795887848
%N A371826 a(n) = Sum_{k=0..floor(n/2)} n^k * binomial(2*n-k,n-2*k).
%F A371826 a(n) = [x^n] 1/((1-x-n*x^2) * (1-x)^n).
%F A371826 a(n) ~ exp(3*sqrt(n)/2) * n^(n/2) / 2. - _Vaclav Kotesovec_, Apr 07 2024
%o A371826 (PARI) a(n) = sum(k=0, n\2, n^k*binomial(2*n-k, n-2*k));
%Y A371826 Cf. A371825, A371827.
%Y A371826 Cf. A171180.
%K A371826 nonn
%O A371826 0,2
%A A371826 _Seiichi Manyama_, Apr 07 2024